code: def test_reservation_environment_exists_get_server_ip_return_environment_value(
      self,
  ):
      tfos_server = Server(5)
      with mock.patch.dict(
          os.environ, {"TFOS_SERVER_HOST": "my_host_ip"}
      ):
          assert tfos_server.get_server_ip() == "my_host_ip"
  
file_path: TensorFlowOnSpark/tests/test_reservation.py
imports: import os
  import threading
  import time
  import unittest
  from tensorflowonspark import util
  from tensorflowonspark.reservation import Reservations, Server, Client
  from unittest import mock
label_desc: Use image node_id 3 for calling the ReservationTest obj's underlying member method code with example usage: obj.test_reservation_environment_exists_get_server_ip_return_environment_value() without return types